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avfilter/vf_scale: add in/out_chroma_loc

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Currently, this just functions as a more principled and user-friendly
replacement for the (undocumented and hard to use) *_chr_pos fields.

However, the goal is to automatically infer these values from the input
frames' chroma location, and deprecate the manual use of *_chr_pos
altogether. (Indeed, my plans for an swscale replacement will most
likely also end up limiting the set of legal chroma locations to those
permissible by AVFrame properties)
This commit is contained in:
Niklas Haas 2024-07-04 13:44:05 +02:00
parent 18b9687308
commit 15a67c0947
2 changed files with 76 additions and 23 deletions
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15
doc/filters.texi
View File

@ -21137,6 +21137,21 @@ Set full range (0-255 in case of 8-bit luma).
Set "MPEG" range (16-235 in case of 8-bit luma).
@end table
@item in_chroma_loc
@item out_chroma_loc
Set in/output chroma sample location. If not specified, center-sited chroma
is used by default. Possible values:
@table @samp
@item auto, unknown
@item left
@item center
@item topleft
@item top
@item bottomleft
@item bottom
@end table
@item force_original_aspect_ratio
Enable decreasing or increasing output video width or height if necessary to
keep the original aspect ratio. Possible values:

84
libavfilter/vf_scale.c
View File

@ -169,6 +169,8 @@ typedef struct ScaleContext {
int in_range;
int out_range;
int in_chroma_loc;
int out_chroma_loc;
int out_h_chr_pos;
int out_v_chr_pos;
int in_h_chr_pos;
@ -618,6 +620,40 @@ fail:
return ret;
}
static void calc_chroma_pos(int *h_pos_out, int *v_pos_out, int chroma_loc,
int h_pos_override, int v_pos_override,
int h_sub, int v_sub, int index)
{
int h_pos, v_pos;
/* Explicitly default to center siting for compatibility with swscale */
if (chroma_loc == AVCHROMA_LOC_UNSPECIFIED)
chroma_loc = AVCHROMA_LOC_CENTER;
/* av_chroma_location_enum_to_pos() always gives us values in the range from
* 0 to 256, but we need to adjust this to the true value range of the
* subsampling grid, which may be larger for h/v_sub > 1 */
av_chroma_location_enum_to_pos(&h_pos, &v_pos, chroma_loc);
h_pos *= (1 << h_sub) - 1;
v_pos *= (1 << v_sub) - 1;
if (h_pos_override != -513)
h_pos = h_pos_override;
if (v_pos_override != -513)
v_pos = v_pos_override;
/* Fix vertical chroma position for interlaced frames */
if (v_sub == 1 && index > 0) {
v_pos += 256 * (index == 2); /* offset by one luma row for odd rows */
v_pos >>= 1; /* double luma row distance */
}
/* Explicitly strip chroma offsets when not subsampling, because it
* interferes with the operation of flags like SWS_FULL_CHR_H_INP */
*h_pos_out = h_sub ? h_pos : -513;
*v_pos_out = v_sub ? v_pos : -513;
}
static int config_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
@ -677,15 +713,16 @@ static int config_props(AVFilterLink *outlink)
inlink0->h == outlink->h &&
in_range == outlink->color_range &&
in_colorspace == outlink->colorspace &&
inlink0->format == outlink->format)
inlink0->format == outlink->format &&
scale->in_chroma_loc == scale->out_chroma_loc)
;
else {
struct SwsContext **swscs[3] = {&scale->sws, &scale->isws[0], &scale->isws[1]};
int i;
for (i = 0; i < 3; i++) {
int in_v_chr_pos = scale->in_v_chr_pos, out_v_chr_pos = scale->out_v_chr_pos;
int in_full, out_full, brightness, contrast, saturation;
int h_chr_pos, v_chr_pos;
const int *inv_table, *table;
struct SwsContext *const s = sws_alloc_context();
if (!s)
@ -709,28 +746,17 @@ static int config_props(AVFilterLink *outlink)
av_opt_set_int(s, "dst_range",
outlink->color_range == AVCOL_RANGE_JPEG, 0);
/* Override chroma location default settings to have the correct
* chroma positions. MPEG chroma positions are used by convention.
* Note that this works for both MPEG-1/JPEG and MPEG-2/4 chroma
* locations, since they share a vertical alignment */
if (desc->log2_chroma_h == 1) {
if (in_v_chr_pos == -513)
in_v_chr_pos = 128; /* explicitly default missing info */
in_v_chr_pos += 256 * (i == 2); /* offset by one luma row for odd rows */
in_v_chr_pos >>= i > 0; /* double luma row distance */
}
calc_chroma_pos(&h_chr_pos, &v_chr_pos, scale->in_chroma_loc,
scale->in_h_chr_pos, scale->in_v_chr_pos,
desc->log2_chroma_w, desc->log2_chroma_h, i);
av_opt_set_int(s, "src_h_chr_pos", h_chr_pos, 0);
av_opt_set_int(s, "src_v_chr_pos", v_chr_pos, 0);
if (outdesc->log2_chroma_h == 1) {
if (out_v_chr_pos == -513)
out_v_chr_pos = 128;
out_v_chr_pos += 256 * (i == 2);
out_v_chr_pos >>= i > 0;
}
av_opt_set_int(s, "src_h_chr_pos", scale->in_h_chr_pos, 0);
av_opt_set_int(s, "src_v_chr_pos", in_v_chr_pos, 0);
av_opt_set_int(s, "dst_h_chr_pos", scale->out_h_chr_pos, 0);
av_opt_set_int(s, "dst_v_chr_pos", out_v_chr_pos, 0);
calc_chroma_pos(&h_chr_pos, &v_chr_pos, scale->out_chroma_loc,
scale->out_h_chr_pos, scale->out_v_chr_pos,
outdesc->log2_chroma_w, outdesc->log2_chroma_h, i);
av_opt_set_int(s, "dst_h_chr_pos", h_chr_pos, 0);
av_opt_set_int(s, "dst_v_chr_pos", v_chr_pos, 0);
if ((ret = sws_init_context(s, NULL, NULL)) < 0)
return ret;
@ -995,6 +1021,8 @@ scale:
out->height = outlink->h;
out->color_range = outlink->color_range;
out->colorspace = outlink->colorspace;
if (scale->out_chroma_loc != AVCHROMA_LOC_UNSPECIFIED)
out->chroma_location = scale->out_chroma_loc;
if (scale->output_is_pal)
avpriv_set_systematic_pal2((uint32_t*)out->data[1], outlink->format == AV_PIX_FMT_PAL8 ? AV_PIX_FMT_BGR8 : outlink->format);
@ -1232,6 +1260,16 @@ static const AVOption scale_options[] = {
{ "mpeg", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_MPEG}, 0, 0, FLAGS, .unit = "range" },
{ "tv", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_MPEG}, 0, 0, FLAGS, .unit = "range" },
{ "pc", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_JPEG}, 0, 0, FLAGS, .unit = "range" },
{ "in_chroma_loc", "set input chroma sample location", OFFSET(in_chroma_loc), AV_OPT_TYPE_INT, { .i64 = AVCHROMA_LOC_UNSPECIFIED }, 0, AVCHROMA_LOC_NB-1, .flags = FLAGS, .unit = "chroma_loc" },
{ "out_chroma_loc", "set output chroma sample location", OFFSET(out_chroma_loc), AV_OPT_TYPE_INT, { .i64 = AVCHROMA_LOC_UNSPECIFIED }, 0, AVCHROMA_LOC_NB-1, .flags = FLAGS, .unit = "chroma_loc" },
{"auto", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_UNSPECIFIED}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"unknown", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_UNSPECIFIED}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"left", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_LEFT}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"center", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_CENTER}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"topleft", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_TOPLEFT}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"top", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_TOP}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"bottomleft", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_BOTTOMLEFT}, 0, 0, FLAGS, .unit = "chroma_loc"},
{"bottom", NULL, 0, AV_OPT_TYPE_CONST, {.i64=AVCHROMA_LOC_BOTTOM}, 0, 0, FLAGS, .unit = "chroma_loc"},
{ "in_v_chr_pos", "input vertical chroma position in luma grid/256" , OFFSET(in_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },
{ "in_h_chr_pos", "input horizontal chroma position in luma grid/256", OFFSET(in_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },
{ "out_v_chr_pos", "output vertical chroma position in luma grid/256" , OFFSET(out_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },